Ejector-type refrigeration systems have long been known employing a single fluid as both a high-velocity propellant or motive gas stream and as a slower moving secondary refrigerant gas stream entrained in and accelerated by the propellant. (The term "refrigeration systems" as used herein shall mean systems functioning in a cooling or refrigeration mode and also in a heating mode as a heat pump). The resulting kinetic energy of the mixture is subsequently used for self-compression to a higher pressure, thus fulfilling the function of a compressor. A full description of such a single-fluid system is set forth in a paper entitled "Investigation Of An Ejector Heat Pump By Analytical Methods" by C. T. Hsu published July 1984 by the Oak Ridge National Laboratory for the United States Department of Energy.
An early article cited therein namely "Performance Of Ejectors As A Function Of The Molecular Weights Of Vapors" by Work and Haedrich, Industrial And Engineering Chemistry, April 1939, pages 464 to 477, suggests employing two separate fluids as the propellant and refrigerant and mentions the problem of separating of the propellant from the refrigerant for recycling back through their respective loops. While it states that separation might be accomplished by gravity separation with immiscible fluids (page 476), it does not disclose any particular immiscible fluids which would be operable for the purpose.
It is the principal purpose of this invention to maximize the coefficient of performance (COP) of an ejector-type refrigeration system by selection of particular immiscible propellant and refrigerant fluids. The invention in particular is directed to pairs of immiscible fluids which not only have a large difference in heat of vaporization but which are also chosen to avoid most of the negative effect of adding of vapor pressures in the condenser. In the condenser the vapor pressures of two immiscible fluids add together making it inefficient for condensation to take place at typically high pressures.